This invention relates to a hitch adapter for a tractor drawbar that provides equal angle articulation of universal joints in the drive assembly that connects the tractor PTO to a driveshaft on a towed implement. An adapter of this general nature is shown in U.S. Pat. No. 3,557,892, which is also assigned to the assignee herein.
In the adapter shown in said patent, equal angle articulation of the front and rear universal joints in the drive assembly are provided by shifting the vertical articulation point between the implement and the tractor drawbar rearwardly, although the vertical load on the tractor drawbar is not affected. This feature is highly desirable when heavier drawbar loads are involved so as not to overload the drawbar. However, in some instances the nature of the towed implement is such that rearward extension of the vertical load on the drawbar does not overload the drawbar, and accordingly, a hitch adapter has been provided whereby both the vertical load and the articulation point between the tractor and the implement are shifted rearwardly. Such an adapter has been offered by the assignee herein for several years, although said adapter is not shown in a patent or patent application. Generally, said adapter included a housing having horizontal top and bottom walls and vertical side walls, the tractor drawbar extending into the housing and being pinned therein by a vertical pin extending through the top and bottom walls and a vertical bore on the end of the drawbar. Adjustment for different drawbar widths was accomplished by a pair of transverse bolts extending through the opposite side walls and engaging the opposite sides of the drawbar, while adjustment for different vertical drawbar thicknesses was accomplished by a similar adjusting bolt extending through the top wall and engageable with the top of the drawbar. A vertical post was provided at the rearward end of the adapter for pivotal connection to the forward end of the implement tongue, the axis of the post being centered between the two universal joints to provide said equal angle articulation.